The present application claims priority to Japanese Patent Application No. 2000-083398, filed Mar. 24, 2000, entitled xe2x80x9cX-ray Sample Testing Apparatusxe2x80x9d. The contents of that application are incorporated herein by reference in their entirety.
1. Field of the Invention
The present invention relates to an optical sample X-ray testing apparatus and a method for testing an optical sample with X-rays. Further, the present invention relates to a method for manufacturing a reflective mask blank configured to be exposed with X-rays and a method for manufacturing a mirror configured to be used in an X-ray optical system.
2. Discussion of the Background
Recently, semiconductor manufacturing techniques are rapidly becoming more detailed and thus the analysis and observation of semiconductor regions are increasingly miniaturized. Along with such a trend, use of X-ray has been increasing in the area of, for example, X-ray optical devices such as X-ray exposure devices, X-ray microscopes and X-ray analyzers. To manufacture these devices, the use of X-ray optical elements such as multi-layered film mirrors, oblique-incidence mirrors, filters, beam splitters is necessary. A key to manufacture a high performance X-ray optical device is how to manufacture optical elements having good optical properties such as reflectivity, transmittance and degree of scattering. In order to make an optical element capable of high performance, an optical element is evaluated by using an X-ray beam having a wavelength intended or a wavelength sufficiently close to be actually used. For example, X-ray exposure devices generally use an X-ray beam having a wavelength in the range of 10 nm to 30 nm, particularly around 11 nm and 13 nm. Thus, it is desirable to evaluate their optical elements using an X-ray beam having a wavelength around that range. Subsequently, by utilizing the result from such evaluation into their manufacturing process, the optical elements are developed and manufactured quickly and efficiently. For example, one of the most important optical properties is reflectivity, and many radiation light facilities around the world have devices for evaluating reflectivity. Nevertheless, such devices are not available for any persons and can be used during limited periods of time. As such, it is difficult to evaluate optical elements for their reflectivity and implement the results quickly into their manufacturing process. Unexamined Japanese Patent Publication (Kokai) Nos. 4-128641 and 10-318945 disclose devices using a laser plasma X-ray. The contents of these publications are incorporated herein by reference in their entirety. In these devices, a laser plasma X-ray source (hereinafter referred to as an xe2x80x9cLPXxe2x80x9d) emits an X-ray beam having a continuous spectrum, and by using a diffraction grating technique, the X-ray beam is spectrally separated. Then, by using a slit, an X-ray beam having a desired wavelength is selected. At the same time, the X-ray beam is limited a certain width with respect to that spectrum. Subsequently, the X-ray beam is irradiated upon an optical element to be measured. The reflectivity of the optical element is thus measured. However, because of the diffraction grating technique, such a method has low efficiency in using an X-ray beam. Also, because the diffraction efficiency is low, the amount of an X-ray beam reaching the optical element is low. As a result, the measurement takes longer and accuracy becomes low due to a low signal to noise ratio. In turn, it takes longer to evaluate, for example, mask blanks and X-ray optical mirrors for X-ray exposure devices during their manufacturing process, resulting in optical devices with low accuracy of measurement at a higher cost.
According to one aspect of the present invention, an optical sample X-ray testing apparatus includes an X-ray source, a line spectrum selecting device and an optical characteristics finding device. The X-ray source is configured to radiate X-rays including a group of line spectra. The line spectrum selecting device is provided between the X-ray source and an optical sample and is configured to direct substantially one line spectrum among the group of line spectra from the X-ray source toward the optical sample. The optical characteristics finding device is configured to find optical characteristics of the optical sample based on radiation of the substantially one line spectrum through the line spectrum selecting device onto the optical sample.
According to another aspect of the present invention, an optical sample X-ray testing apparatus includes an X-ray source and a line spectrum selecting device. The X-ray source is configured to radiate X-rays including a group of line spectra. The line spectrum selecting device is provided between the X-ray source and an optical sample and configured to direct substantially one line spectrum among the group of line spectra from the X-ray source toward the optical sample to find optical characteristics of the optical sample.
According to yet another aspect of the present invention, an optical sample X-ray testing apparatus includes an X-ray source, a multi-layered film mirror and an optical characteristics finding device. The X-ray source is configured to radiate X-rays including a continuous spectrum. The multi-layered film mirror is provided between the X-ray source and an optical sample and is configured to reflect only X-rays having a band range determined by the multi-layered film mirror among X-rays from the X-ray source toward the optical sample. The optical characteristics finding device is configured to find optical characteristics of the optical sample based on radiation of the X-rays having the band range determined by the multi-layered film mirror onto the optical sample.
According to further aspect of the present invention, a method for testing an optical sample with X-rays includes generating X-rays including a group of line spectra. Substantially one line spectrum among the group of line spectra is directed toward an optical sample. Optical characteristics of the optical sample are found based on radiation of the substantially one line spectrum onto the optical sample.
According to yet further aspect of the present invention, a method for testing an optical sample with X-rays includes generating X-rays including a continuous spectrum. Only X-rays having a band range determined by a multi-layered film mirror among the X-rays are reflected on the multi-layered film mirror toward an optical sample. Optical characteristics of the optical sample are found based on radiation of the X-rays having the band range determined by the multi-layered film mirror onto the optical sample.
According to the other aspect of the present invention, a method for manufacturing a reflective mask blank includes producing a mask blank configured to be exposed with X-rays. X-rays including a group of line spectra are generated. Substantially one line spectrum among the group of line spectra is directed toward the mask blank. Reflectivity of the mask blank is found based on radiation of the substantially one line spectrum onto the mask blank.
According to yet another aspect of the present invention, a method for manufacturing a mirror includes producing a mirror configured to be used in an X-ray optical system. X-rays including a group of line spectra are generated. Substantially one line spectrum among the group of line spectra is directed toward the mirror. Reflectivity of the mirror is found based on radiation of the substantially one line spectrum onto the mirror.
According to the other aspect of the present invention, a method for manufacturing a reflective mask blank includes producing a mask blank configured to be exposed with X-rays. X-rays including a continuous spectrum is generated. Only X-rays having a band width determined by a multi-layered mirror among the X-rays is reflected on the multi-layered mirror toward the mask blank. Reflectivity of the mask blank is found based on radiation of the X-rays having the band width onto the mask blank.
According to yet another aspect of the present invention, a method for manufacturing a mirror includes producing a mirror configured to be used in an X-ray optical system. X-rays including a continuous spectrum is generated. Only X-rays having a band width determined by a multi-layered mirror among the X-rays is reflected on the multi-layered mirror toward the mirror. Reflectivity of the mirror is found based on radiation of the X-rays having the band width onto the mirror.